Core class used for upgrading/installing plugins.

Plugin Upgrader Skin for WordPress Plugin Upgrades.

Theme Installer Skin for the WordPress Theme Installer.

Core class used for upgrading/installing themes.

Theme Upgrader Skin for WordPress Theme Upgrades.

Upgrader Skin for Ajax WordPress upgrades.

Constructor.

Stores an error message about the upgrade.

Stores a message about the upgrade.

Retrieves a string for error messages.